JPH059608Y2 - - Google Patents

Description

[Detailed Description of the Invention] [Industrial Application Field] The present invention relates to a height measuring device used, for example, for adjusting tape guide assembly on a video tape recorder (VTR) manufacturing line.

[Summary of the invention] This invention places a height sensor on a reference base at a certain distance from the horizontal reference plane, and a measuring element that contacts the flange of the object to be measured directly below the height sensor. In the height measuring device, the height sensor is arranged to be movable up and down in the vertical direction and measures the distance from the reference surface to the measuring tip at the time of contact, and the height sensor is arranged such that the height sensor measures the distance between the reference base and the measuring tip. , a direction conversion means for converting the vertical movement of the measuring stylus into a horizontal rotational movement is provided in a preparatory stage before the start of measurement by the height sensor, and this direction conversion means is provided protruding from the reference surface side of the reference base, By comprising a cam having a cam surface inclined to the side, a cam follower protruding from the measuring head and engaging with the cam surface of the cam, and an elastic member interposed between these cams and the cam follower. , the height of the flange of the object to be measured is determined by approaching the stylus from directly above and to the side of the object to be measured, and bringing the stylus close to and in contact with the flange of the object without moving the height measuring device horizontally. can be measured using a simple mechanism.

[Prior Art] For example, in a video tape recorder (VTR), the height of a tape guide located near a rotating head drum (if a flange is formed at the upper end of the tape guide, the height of the lower surface of the flange) If the position (or the position of the upper surface of the flange in the case where the flange is formed at the lower end) is misaligned, it will not be possible to obtain a proper tape path, and the track position on the tape will fluctuate, causing problems in recording and playback. Because of this, it is necessary to properly adjust the height of the tape guide. In a so-called 8 mm VTR, the permissible deviation in track position on the tape is within 2 .mu.m, and for this purpose, the deviation in the height position of the tape guide must be adjusted to within about 10 .mu.m.

Conventionally, height measuring devices are known for adjusting the height of the tape guide. To explain this in detail with reference to FIG. 3, reference numeral 1 denotes a height measuring device, and a fixed base 3 is fixed to the reference surface (lower surface) 2a of the reference base 2 with screws 4. . On the fixed base 3, an eddy current type proximity height sensor 5 is arranged vertically protruding from the lower side thereof, and a support shaft 7 having a metal plate-shaped measuring element 6 penetrated through the reference base 2. It is arranged so that it can be moved up and down.

The height sensor 5 is fastened and fixed to the fixed base 3 with a screw 8 so that the distance l ₁ from its tip to the reference surface 2a of the reference base 2 is a constant value. The height sensor 5 is connected to the display 1 via a signal processing circuit 11 including an amplifier 9, an A/D converter 10, and a microcomputer.
It is electrically connected to 2.

Further, the measuring element 6 is screwed to the lower end of the support shaft 7 and is located directly below the height sensor 5. The support shaft 7 is movable up and down by a bearing 13 fitted in the fixed base 3, and is constantly moved upward by a compression coil spring 14 interposed between the bearing 13 and the upper part of the support shaft 7. It is energized.

Note that the reference numeral 21 is a tape guide as an object to be measured. This tape guide 21 has a flange 22 at the upper end.
has been formed. Also, the code l is the tape guide 2
1, that is, the distance from the reference surface 2a of the reference base 2 to the lower surface 22a of the flange 22, and _l2 is the distance from the tip of the height sensor 5 to the upper surface 6a of the measuring tip 6.

When measuring the height of the tape guide 21 (the position of the lower surface 22a of the flange 22) using the height measuring device 1 configured as described above, first, the tip of the measuring stylus 6 touches the flange of the tape guide 21. At a place slightly horizontally shifted from directly above the flange 22 that does not touch the part 22, the support shaft 7 that fixes the probe 6 is moved by a compressed coil spring 14 using an air cylinder (not shown).
The contact point 6 is pressed downward against the urging force of , and the contact point 6 is lowered to the position indicated by the two-dot chain line in the figure. Next, the reference base 2 is moved horizontally and the tape guide 2 is
Close to 1. When the air from the air cylinder is extracted in this state, the probe 6 moves upward due to the biasing force of the compression coil spring and comes into contact with the lower surface 22a of the flange 22 of the tape guide 21. In this state, the height sensor 5 outputs a signal corresponding to the distance l ₂ between the height sensor 5 and the upper surface 6a of the probe 6. The output signal of the height sensor 5 is supplied to an A/D converter 10 via an amplifier 9, where it is converted into a digital signal and then supplied to a signal processing circuit 11. This signal processing circuit 11
In , the output signal is multiplied by a voltage/distance conversion coefficient k to calculate the distance l ₂ . As a result, the height of the tape guide 21, that is, the height of the reference base 2
The distance l from the reference surface 2a to the lower surface 22a of the flange 22 of the tape guide 21 is calculated as l ₁ +l ₂ . If there is a deviation from the set value of the height l calculated by this signal processing circuit 11, and this deviation is within a certain tolerance range, for example, within 10μ, "OK" is displayed on the display 12, In addition, if it is not within a certain tolerance range, the indicator 12
"NG" is displayed. Based on this display, the height of the tape guide 21 can be adjusted.

[Problems to be solved by the invention] However, in the conventional height measuring device 1, after the measuring element 6 descends from a certain distance directly above the tape guide 21, it further moves in the horizontal direction. There are two moving steps close to the tape guide 21, and a space is required for the horizontal movement of the probe 6. For example, in a comprehensive assembly state where complicated mechanisms are crowded together on a VTR production line, It was difficult to measure the height l of the tape guide 21 because the measuring element 6 came into contact with other components.

Therefore, this invention provides a height measuring device that can measure the height of an object to be measured even in a small space.

[Means for solving the problem] In a height measuring device in which a height sensor is placed on a reference base at a fixed distance from its horizontal reference surface, a probe that abuts against the flange of an object to be measured is disposed directly below the height sensor so as to be freely movable up and down in the vertical direction, and the height sensor measures the distance from the reference surface to the probe at the time of abutment. Between the reference base and the probe, a direction changing means is provided for changing the up and down movement of the probe into horizontal rotational movement in a preparation stage before measurement by the height sensor begins, and this direction changing means is composed of a cam that protrudes from the reference surface side of the reference base and has a cam surface inclined toward its tip, a cam follower that protrudes from the probe and engages with the cam surface of the cam, and an elastic member that is interposed between the cam and the cam follower.

[Operation] The measuring element is lowered from approximately directly above the object to be measured after its direction is changed and it is removed from the flange of the object to be measured.
Thereafter, the measuring stylus is returned to its original direction and brought into contact with the flange, thereby positioning the measuring stylus. When this contact point contacts the flange of the object to be measured and is positioned, the height sensor measures the distance from the reference surface of the reference base to the contact point (specific position).
The height of the object to be measured is determined.

[Example] Hereinafter, an example of this invention will be described in detail with reference to the drawings. Incidentally, the same parts as in the prior art are given the same reference numerals, and detailed explanation thereof will be omitted.

In Figures 1 and 2, reference numeral 1 is a height measuring device used to measure the height l of the tape guide 21 of the VTR, and the fixed base 3 is fastened and fixed to the reference surface 2a of the reference base 2 with screws 4. This is the same as in the prior art in that the fixed base 3 is provided with a height sensor 5 connected to an amplifier 9, etc., and a measuring element 6 that is movable up and down via a support shaft 7. Here, a plate cam 15 as a cam is fastened and fixed to the lower surface of the fixed base 3 in parallel to the height sensor 5 and the support shaft 7 with screws 16. A cam surface 15 that slopes outward from the middle of one end surface of the plate cam 15 on the probe 6 side to the tip.
A is formed. A rod-shaped cam follower 17 that engages with the cam surface 15a of the plate cam 15 is provided at the base of the side surface of the plate cam 15 of the plate cam 15 on the plate cam 15 side, protruding parallel to the reference surface 2a of the reference base. It has been done. A tension coil spring 18 as an elastic member is interposed at a predetermined position on the tip of the cam follower 17 and on the side surface of the plate cam 15 opposite to the side surface where the height sensor 5 is located. This tension coil spring 1
8 and a compression coil spring 14 that urges the measuring element 6 upward, the upper surface 6a of the measuring element 6 is normally positioned directly below the tip of the height sensor 5 and is in surface contact with the tip. These plate cams 15, cam followers 17, and tension coil springs 18 constitute direction changing means 19 for changing the direction of the probe 6 from vertical movement to horizontal rotational movement.

The side surface of the probe 6 opposite to the side surface facing the plate cam 15 protrudes outward from the axial direction of the support shaft 7, and a ball 20 is caulked and fixed to the center of the lower part of the side surface.

According to the apparatus of the above embodiment, the tape guide 21
, that is, the height l of the flange 22 of the tape guide 21
When measuring the position of the lower surface 22a of is horizontally rotated toward the plate cam 15 side by the plate cam 15, cam follower 17, etc., and the side surface with the ball 20 is kept in a state where it is removed to approximately right below the height sensor 5. From this state, the measuring element 6 is brought close to the flange 22 of the tape guide 21 by vertically moving it downward by a predetermined means (indicated by the two-dot chain line in FIG. 1).

Next, when the air is released from the air cylinder, the probe 6 is moved upward by the urging force of the compression coil spring 14 and the tension coil spring 18, and horizontally rotated toward the tape guide 21 to change its direction. The ball 20 of the measuring element 6 comes into contact with the circumferential surface of the tape guide 21, and the upper surface 6 of the measuring element 6
a comes into contact with the lower surface 22a of the flange 22 of the tape guide 21. This contact completes the positioning of the probe 6, and the height l of the tape guide 21 is calculated as l ₁ + l ₂ by the height sensor 5, signal processing circuit 11, etc. and can be measured as in the conventional case. can.
When there is a deviation from the set value of the height l of the tape guide 21, if this deviation is within a certain tolerance range, for example within 10μ, the indicator 12
“OK” is displayed on the display 12, and “NG” is displayed on the display 12 when the value is not within a certain allowable range. Based on this display, the height of the tape guide 21 can be adjusted.

In this way, when measuring the height of the tape guide 21, the measuring element 6 is moved toward the tape guide 21 by the direction changing means 19, which is a simple mechanism consisting of the plate cam 15, etc.
Since the direction can be changed by lowering the tape guide 21 from almost directly above it and bringing it close to the flange 22 of the tape guide 21, the height of the tape guide 21 can be adjusted, for example, when the tape guide 21 is assembled in a state where complicated mechanisms are crowded together on a VTR manufacturing line. In this case, the height l of the tape guide 21 can be easily adjusted by inserting the probe 6 in a direction where it does not come into contact with other components or from a small space and bringing it close to the tape guide 21. can be measured.

According to the embodiment, "OK" and "NG" are displayed on the display 12, but the numerical value of the height may be specifically displayed. Further, although the case where the present invention is used to measure the height of the tape guide 21 of a VTR is shown, the present invention is not limited to the tape guide 21 and can be applied to the height measurement of other objects to be measured.

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[Effects of the invention] As described above, according to the height measuring device of this invention, the measuring head is lowered from almost directly above the object to be measured by using the direction changing means of a simple mechanism such as a cam. By making it possible to change the direction so as to make contact with the flange of the probe, the height of the object to be measured can be easily measured as long as there is a small space in which the probe can fit.

[Brief explanation of the drawing]

FIG. 1 is a perspective view of a height measuring device showing an embodiment of this invention, FIG. 2 is a front view thereof, and FIG. 3 is a configuration diagram of a conventional example. 1...Height measuring device, 2...Reference base, 2a
... Reference surface, 5 ... Height sensor, 6 ... Measuring head, 15 ... Plate cam (cam), 15a ... Cam surface,
17... Cam follower, 18... Tension coil spring (elastic member), 19... Direction changing means, 21...
... Tape guide (object to be measured), 22 ... Flange, l
... Height of the object to be measured, l ₁ ... Distance from the reference plane to the height sensor, l ₂ ... Distance from the height sensor to the flange.

Claims (1)

[Scope of utility model registration request] A height sensor is placed on the reference base at a certain distance from the horizontal reference plane, and a measuring tip that contacts the flange of the object to be measured is placed directly below the height sensor so that it can move up and down in the vertical direction. In the height measuring device, the height sensor measures the distance from the reference surface to the measuring tip at the time of contact, between the reference base and the measuring tip, before the height sensor starts measuring. In the preparation stage, a direction converting means for converting the vertical movement of the probe into a horizontal rotational movement is provided, and this direction converting means is replaced by a cam projecting from the reference surface side of the reference base and having a cam surface inclined toward the tip side. A height measuring device comprising: a cam follower projecting from the measuring element and engaging with a cam surface of the cam; and an elastic member interposed between the cam and the cam follower.